Structure of very high insertion loss of the substrate noise decoupling

ABSTRACT

A structure includes a substrate comprising a region having a circuit or device which is sensitive to electrical noise. Additionally, the structure includes a first isolation structure extending through an entire thickness of the substrate and surrounding the region and a second isolation structure extending through the entire thickness of the substrate and surrounding the region.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of U.S. application Ser. No.11/942,811, filed on Nov. 20, 2007 the disclosure of which is expresslyincorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to a structure and method using dualthrough-wafer vias for substrate to device/circuit coupling noisereduction or increased insertion loss, and the design structure on whichthe subject circuit structure resides.

BACKGROUND OF THE INVENTION

In an integrated circuit, a signal can couple from one node to anothervia the substrate. This phenomenon is referred to as substrate couplingor substrate noise coupling. Moreover, a substrate that is susceptibleto substrate noise coupling may be described as having a low insertionloss, where insertion loss is a decrease in transmitted signal.Substrate noise coupling remains one of the main concerns in low noisecircuits for mixed signal and system-on-chip (SOC) designs.

The push for reduced cost, more compact integrated circuit systems, andadded customer features has provided incentives for the inclusion ofanalog functions on primarily digital integrated circuits (ICs) formingmixed-signal ICs. In these systems, the speed of digital circuits isconstantly increasing, chips are becoming more densely packed,interconnect layers are added, and analog resolution is increased. Inaddition, recent increases in wireless applications and its growingmarket are introducing a new set of aggressive design goals forrealizing mixed-signal systems.

However, in mixed-signal systems, both sensitive analog circuits andhigh-swing, high-frequency noise injector digital circuits may bepresent on the same chip, leading to undesired signal coupling betweenthese two types of circuits via the conductive substrate. Additionally,the reduced distance between these circuits, which is the result ofconstant technology scaling, exacerbates the noise coupling.

A challenging task, applicable to any mixed-signal IC, is to minimizenoise coupling between various parts of the system to avoid anymalfunctioning of the system. In other words, for successfulsystem-on-chip integration of mixed-signal systems, the noise couplingcaused by non-ideal isolation should be minimized so that sensitiveanalog circuits and noisy digital circuits can effectively coexist, andthe system operates correctly.

The primary mixed-signal noise coupling problem comes from fast-changingdigital signals coupling to sensitive analog nodes. Another significantcause of undesired signal coupling is the cross-talk between analognodes themselves owing to high-frequency/high-power analog signals. Oneof the media through which mixed-signal noise coupling occurs is thesubstrate. Digital operations cause fluctuations in the underlyingsubstrate voltage, which spreads through the common substrate causingvariations in the substrate potential of sensitive devices in the analogsection. Similarly, in the case of cross talk between analog nodes, asignal can couple from one node to another via the substrate.

Additionally, substrate noise coupling is a concern with low noiseamplifiers (LNAs). A LNA is a special type of electronic amplifier oramplifier used in communications systems to amplify very weak signalscaptured by an antenna, e.g., of a radio frequency telescope. The LNAmay be located close to the antenna, such that the losses in the signalpath become less critical. Using a LNA, the noise of all subsequentstages is reduced by the gain of the LNA and the noise of the LNA isinjected directly into the received signal. Thus, it is desirable for aLNA to boost the desired signal power while adding as little noise anddistortion as possible so that the retrieval of this signal is possiblein the later stages in the system.

Furthermore, substrate noise coupling is a concern with phase-lockedloop (PLL) systems. A PLL is an electronic control system that generatesa signal that is locked to the phase of an input or “reference” signal.This circuit compares the phase of a controlled oscillator to thereference, automatically raising or lowering the frequency of theoscillator until its phase (and therefore frequency) is matched to thatof the reference. Phase-lock loops are widely used in radio,telecommunications, computers and other electronic applications togenerate stable frequencies, or to recover a signal from a noisycommunication channel. Since a single integrated circuit can provide acomplete phase-lock-loop building block, the technique is widely used inmodern electronic devices, with output frequencies from a fraction of acycle per second up to many gigahertz. However, because the PLL isformed on a single integrated circuit, the device is susceptible tosubstrate noise coupling. For example, in a cellular phone transceiver,when the pre-driver operates, the PLL output becomes very noisy due tocoupling with the substrate.

Conventionally, in attempting to minimize substrate noise coupling,designers have used deep and shallow trench isolations, guard ringstructures and high doping layer/triple well structures. However, eachof these noise isolation techniques suffer from drawbacks.

For example, deep and shallow trench isolations are too shallow and haveno bottom, and thus cannot completely isolate substrate noise oreliminate substrate noise coupling. More specifically, deep trenchisolations are typically 3 to 10 microns in depth and shallow trenchisolations are typically 0.3 to 2 microns in depth. However, the depthof a substrate in which these deep or shallow trench isolations may beformed is typically at least 250 microns. Thus, noise has enough path inthe substrate to bypass the deep and/or shallow trench isolations.

Moreover, guardrings, which are a type of trench isolation, aretypically made of metal and formed by lithography and etch processing.However, these techniques may have the low insertion loss at highfrequencies due to the parasitic capacitance and the shallow depth,which may render the device unsuitable for high frequency operations.

Accordingly, there exists a need in the art to overcome the deficienciesand limitations described hereinabove.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a structure comprises a substratecomprising a region having a circuit or device which is sensitive toelectrical noise. Additionally, the structure comprises a firstisolation structure extending through an entire thickness of thesubstrate and surrounding the region and a second isolation structureextending through the entire thickness of the substrate and surroundingthe region.

In an additional aspect of the invention, a method comprises forming atleast one via filled with a dielectric and at least one via filled withmetal in a substrate. Additionally, the method comprises removing asurface portion of the substrate to expose at least the metal andforming a metal layer in contact with at least the exposed metal toprovide an electrical noise isolation area on the substrate.

In a further aspect of the invention, a design structure is embodied ina machine readable medium for designing, manufacturing, or testing adesign, wherein the design structure comprises a substrate comprising aregion having a circuit or device which is sensitive to electricalnoise. Additionally, the design structure comprises a first isolationstructure extending through an entire thickness of the substrate andsurrounding the region and a second isolation structure extendingthrough the entire thickness of the substrate and surrounding theregion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIGS. 1-9 show process steps for forming a final structure shown in FIG.10 in accordance with an aspect of the invention;

FIG. 10 shows an embodiment of a final structure according to an aspectof the invention;

FIGS. 11-15 show top views of alternative embodiments of the invention;

FIG. 16 shows a simulation result graph of substrate noise versusfrequency comparing the present invention with known devices; and

FIG. 17 is a flow diagram of a design process used in semiconductordesign, manufacturing, and/or testing.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a structure and method using dualthrough-wafer vias (TWVs) for substrate to device/circuit coupling noisereduction or increased insertion loss, and the design structure on whichthe subject circuit structure resides. According to an aspect of theinvention, an isolation structure comprises both low impedance and highimpedance structures. More specifically, the isolation structurecomprises a very low impedance grounded metal through-wafer viastructure, a high impedance dielectric (e.g., silicon dioxide (SiO₂))through-wafer via structure, and a surface (e.g., a bottom surface)structure. Thus, according to an embodiment of the invention, anisolation structure comprises a substrate having at least one metalthrough-wafer via (or a through-wafer via filled with metal), at leastone dielectric (e.g., SiO₂) through-wafer via (or a through-wafer viafilled with a dielectric), and a metal layer formed on a surface (e.g.,a bottom surface) of the substrate connecting with at least the metalthrough-wafer via. Moreover, in embodiments the isolation structureprovides, within the innermost through-wafer via structure, a protectionarea having a high insertion loss and low noise coupling.

By using a combination of both low impedance structures (metalthrough-wafer via) and high impedance structures (SiO₂ through-wafervia), the isolation structure provides isolation over an entire range ofimpedances. This may be thought of as analogous to providing a low passfilter and a high pass filter to effectively cover an entire range offrequencies. Additionally, by providing the grounded metal layerconnected to the four walls of the metal through-wafer vias, an enclosedor substantially enclosed structure is provided. Moreover, by usingmetal as the outermost layer, where the conductivity of the metal isvery high, the insertion loss within the protection area of thestructure can be very high and the susceptibility to substrate noisecoupling may be very low.

By implementing the invention, substrate noise coupling is reduced andnoise isolation increased. Additionally, by providing the structurehaving TWVs formed through the depth of the substrate, the noise bypasspath is eliminated. Moreover, the metal TWVs have no parasiticassociated with them, so that the insertion loss has good high frequencyperformance. Additionally, by providing the through-wafer vias inmultiple turns, further noise isolation, higher insertion loss, andlower substrate noise coupling may be achieved. Additionally, byimplementing aspects of the invention, the whole structure can bescalable.

Structure Formation Process

FIG. 1 shows a sectional side view of a beginning structure inaccordance with the invention. The beginning structure comprises asubstrate 10 having inner vias 20 and outer vias 60 etched therein. Inembodiments, the substrate 10 may be, for example, a silicon substrateor a silicon-on-insulation (SOI) substrate. Moreover, the substrate 10may be approximately 700-800 microns in thickness, with otherthicknesses contemplated by the invention. The inner vias 20 and outervias 60 may be formed according to a conventional via formation process,e.g., a lithography and etching process (e.g., a reactive ion etch(RIE)). As such, a description of the lithography and etch process isnot necessary for a person of ordinary skill in the art to practice thisparticular step.

Additionally, while the inner vias 20 and the outer vias 60 are shown inFIG. 1 as discrete elements, it should be understood that the vias maybe formed in a ring structure such that the outer vias 60 are actually asingle via in a ring formation, and the inner vias 20 are a single viain a ring formation. Moreover, the inner vias 20 define a protectionarea 15 on the substrate 10, on which a device or a circuit (not shown)may be formed. In embodiments, the device or the circuit may be formedin the protection area 15 prior to formation of the inner vias 20 andouter vias 60.

Moreover, the inner vias 20 and outer vias 60 may be about 50-250microns in depth, with other depths contemplated by the invention.Additionally, it should be understood that, while inner vias 20 andouter vias 60 are shown as etched to a depth through a portion of thethickness of the substrate 10, the vias 20, 60 may be etched completelythrough the entire thickness of the substrate 10.

Furthermore, the inner and outer vias 20, 60 may be about 50 micronslong and about 3μ wide. As described further below, some of the vias maybe filled with a dielectric (e.g., SiO₂) and the other vias may befilled with a metal. Wider vias (and the material that will fill thevias, as described further below) may allow for better noise isolation.The vias that will contain the metal may have a smaller width than thevias that will contain the SiO₂. Moreover, as wider vias will consumemore device space, the width of the vias 20, 60 may be designed based onbalancing process versus performance.

Additionally, the adjacent inner via 20 and outer via 60 on each side ofthe protection area 15 may be spaced from one another at a minimum ofseveral microns (pitch may be about 9μ). Moreover, the adjacent innervia 20 and outer via 60 on each side of the protection area 15 may bespaced from one another at a distance greater than the minimum distance.However, in embodiments, the distance between the adjacent inner via 20and outer via 60 may be designed as small as possible to reduce theoverall structure size.

FIG. 2 shows the structure after further processing steps. As shown inFIG. 2, a metal has been deposited in the inner vias 20 and outer vias60 to form metal vias 30. The wafer surface has also been polished orplanarized. In embodiments, the metal may comprise, for example, copperor tungsten. The metal may be deposited, for example, through aconventional deposition process and the wafer surface may be polished orplanarized by a conventional process, such as a chemical-mechanicalpolish (CMP). As such, descriptions of the deposition process and thepolishing process are not necessary for a person of ordinary skill inthe art to practice this particular step.

FIG. 3 shows the structure after a further processing step. As shown inFIG. 3, a sacrificial layer 40, e.g., a Si₃N₄ cap film, has beendeposited on the top of the substrate 10 and over the metal vias 30formed in the inner vias 20 and outer vias 60. In embodiments, thesacrificial layer 40 may be formed, for example, by a conventionalchemical vapor deposition (CVD). As such, a description of the CVDprocess is not necessary for a person of ordinary skill in the art topractice this particular step.

FIG. 4 shows the structure after a further processing step. As shown inFIG. 4, the sacrificial layer 40 has been etched to form openings 50aligned with the outer vias 60 to expose the metal 30 deposited in theouter vias 60. The sacrificial layer 40 may be etched using lithographyand an RIE process, a description of which is not necessary for a personof ordinary skill in the art to practice this particular step.

FIG. 5 shows the structure after a further processing step. As shown inFIG. 5, the metal 30 deposited in the outer vias 60 has been removed tore-expose the outer vias 60. In embodiments, the metal may be removedby, for example, a conventional etching with a wet chemical. As such, adescription of the wet etch process is not necessary for a person ofordinary skill in the art to practice this particular step.

FIG. 6 shows the structure after a further processing step. As shown inFIG. 6, an SiO₂ layer 70 may be deposited over the sacrificial layer 40to fill the outer vias 60 to form SiO₂ vias 80. In embodiments, the SiO₂layer 70 may be formed by, for example, a conventional conformal depositof SiO₂. As such, a description of the conformal deposit process is notnecessary for a person of ordinary skill in the art to practice thisparticular step.

FIG. 7 shows the structure after a further processing step. As shown inFIG. 7, the SiO₂ layer 70 may be removed, while leaving the SiO₂ vias80. In embodiments, the SiO₂ layer 70 may be removed, for example, by aconventional polishing step. As such, a description of the polishingprocess is not necessary for a person of ordinary skill in the art topractice this particular step.

While the invention has been described as first depositing a metal inthe inner and outer vias 20, 60 to form metal vias 30 followed by adeposition of SiO₂ in some of the subsequently re-exposed vias to formSiO₂ vias 80, the invention contemplates that the order of thedepositions of the metal and the SiO₂ may be reversed. That is, theinvention contemplates that the SiO₂ layer 70 may first be deposited toform the SiO₂ vias 80, followed by a metal deposition to form the metalvias 30 (after a removal of SiO₂ from some of the SiO₂ vias 80 tore-expose those vias).

Furthermore, while the invention has been described as etching the innerand outer vias 20, 60 during the same processing step (see FIG. 1),followed by the formation of the metal vias 30 and SiO₂ vias 80, theinvention contemplates separate etching steps for the inner and outervias 20, 60. According to this embodiment, the inner vias 20, forexample, may be etched and filled to form the metal vias 30. After asacrificial layer deposition and etch to form openings, a subsequentetch may form the outer vias 60, which may then be filled with SiO₂, toform the SiO₂ vias 80.

FIG. 8 shows the structure after a further processing step. As shown inFIG. 8, the sacrificial layer 40 may be stripped off and an uppersurface of the substrate may be polished by a conventionalchemical-mechanical polish or planarization (CMP) process, such that thesurface of the SiO₂ vias 80 are planar with the top of the substrate 10.As such, a description of the CMP process is not necessary for a personof ordinary skill in the art to practice this particular step.

FIG. 9 shows the structure after a further processing step. As shown inFIG. 9, a bottom portion of the substrate 10 may be removed to exposethe ends (or a surface) 30 a of the metal vias 30 and the ends (or asurface) 80 a of the SiO₂ vias 80. By removing the bottom portion of thesubstrate 10, the metal vias 30 and the SiO₂ vias 80 effectively becomethrough-wafer vias (TWVs). In embodiments, the bottom portion of thesubstrate 10 may be removed through a conventional grinding or polishingprocess. As such, a description of the grinding process is not necessaryfor a person of ordinary skill in the art to practice this particularstep.

As discussed above, the inner vias 20 and outer vias 60 may be formed asTWVs by etching completely through the substrate 10 when the vias 20, 60are initially formed (see FIG. 1). However, it may be more costeffective to form the inner and outer vias 20, 60 as shown in FIG. 1,and subsequently remove the bottom portion of the substrate 10 asdescribed above.

FIG. 10 shows an embodiment of a final isolation structure 100 after afurther processing step according to an aspect of the invention. Asshown in FIG. 10, a metal layer 90 may be formed on a surface (e.g., abottom surface) of the substrate 10 to connect with at least the metalvias 30. In embodiments, the metal layer 90 may extend over the entirebottom of the substrate 10, may extend to the edges of the outermostthrough-wafer vias (SiO₂ vias 80 in the embodiment shown in FIG. 10), ormay extend to the metal vias 30. Additionally, while there is usuallymore space on the bottom surface of the substrate 10 to accommodate themetal layer 90 (e.g., there may be fewer devices or no devices formed onthe bottom surface of the substrate 10), in embodiments, the metal layer90 may be formed on another surface (e.g., an upper surface) of thesubstrate 10. The combination of the metal layer 90, the metal vias 30and the SiO₂ vias 80 forms an enclosed or substantially enclosedstructure. This in turn, creates an isolation region for a device orcircuit.

In optional embodiments, the isolation structure may not use the metallayer 90. That is, a structure having metal through-wafer vias 30 andSiO₂ through-wafer vias 80 without the metal layer 90 is alsocontemplated by the invention. Although such a structure may provideless noise isolation than a structure that includes the metal layer 90,it still provides improved noise isolation compared to known structures.

In embodiments, the metal layer 90 may be formed, for example, through aconventional evaporative process or by a deposition process. As such, adescription of the evaporative process or the deposition process is notnecessary for a person of ordinary skill in the art to practice thisparticular step. Furthermore, in embodiments, the same metal used toform metal vias 30, e.g., copper or tungsten, may be used to form themetal layer 90. The metal layer 90 may be a few microns in thickness,with other thicknesses contemplated by the invention. Moreover, thestructure 100 may be approximately 50-300 microns in thickness, withother thicknesses contemplated by the invention.

By connecting the metal layer 90 with the metal through-wafer vias 30(in a continuous ring formation) a metal box or ring (formed by themetal through-wafer vias 30 and the metal layer 90) of high conductivityis formed. In embodiments, the metal box is a five-wall metal box;although other configurations are contemplated by the invention.Moreover, in use, the metal box is connected to 0V and provides a lowimpedance to the substrate noise, while the SiO₂ through-wafer via 80provides a high impedance to the substrate noise. Together, the metalbox or ring and the SiO₂ through-wafer vias 80 provide an isolationstructure 100 having a high insertion loss, which minimizes substratenoise coupling.

FIG. 11 shows a top view of isolation structure 100 according to anaspect of the invention. As shown in FIG. 11, the structure 100comprises an outer SiO₂ via 80 in a continuous ring formation and aninner metal via 30 in a continuous ring formation formed in thesubstrate 10. Moreover, the structure 100 has a protected area 15surrounded by both the SiO₂ via 80 and the metal via 30.

FIG. 12 shows a top view of an isolation structure 105 according to afurther aspect of the invention. As shown in FIG. 12, while the outerSiO₂ via 80 is formed in the substrate 10 in a continuous ringformation, the metal vias 30 are formed in a segmented ring formation.That is, the metal vias 30 may be formed as a series of discrete vias ina ring formation. In embodiments, it may be preferable for either orboth of the metal vias 30 and the SiO₂ vias 80 to be formed in acontinuous ring formation. However, the vias may be designed based onbalancing process versus performance. Therefore, the inventioncontemplates a range of widths for the discrete vias and otherformations based upon design considerations.

FIG. 13 shows a top view of an isolation structure 110 according to afurther aspect of the invention. As shown in FIG. 13, both the innermetal vias 30 and the outer SiO₂ vias 80 may be formed in a segmentedring formation. Moreover, the inner metal vias 30 and the outer SiO₂vias 80 may be arranged in an offset manner relative to one another,such that there is no direct path from an outside of the outer vias(SiO₂ vias in this embodiment) to the protected (or isolation) area 15.This arrangement provides an effective enclosure about the protectedarea 15.

FIG. 14 shows a top view of an isolation structure 115 according to afurther aspect of the invention. As shown in FIG. 14, the metal via 30and the SiO₂ vias 80 have been reversed as compared to FIG. 12. That is,the SiO₂ vias 80 are formed as the inner vias and the metal via 30 isformed as the outer via in the substrate 10. Moreover, the SiO₂ vias 80are formed in a segmented ring formation, while the metal via 30 isformed in a continuous ring formation.

FIG. 15 shows a top view of an isolation structure 120 according to afurther aspect of the invention. As shown in FIG. 15, the structure 120may comprise multiple turns, or multiple SiO₂ through-wafer vias 80 inring formations and/or multiple metal through-wafer vias 30 in ringformations. By providing multiple turns, or multiple SiO₂ through-wafervias 80 and/or multiple metal through-wafer vias 30, further noiseisolation may be achieved. Moreover, as shown in FIG. 15, the metal vias30 are formed in a segmented ring formation.

However, it should be understood that the SiO₂ vias 80 and metal vias 30need not be arranged in an alternating pairs. That is, in embodiments,the structure may be formed of two metal vias 30 in ring formations witha single SiO₂ via 80 in a ring formation formed therebetween.Alternatively, in embodiments, two metal vias 30 in ring formations maybe formed with a single SiO₂ via 80 in a ring formation formed inside oroutside of the two metal vias 30. Moreover, in embodiments, thestructure may be formed of two SiO₂ vias 80 in ring formations with asingle metal via 30 in a ring formation formed therebetween.Alternatively, in embodiments, two SiO₂ vias 80 in ring formations maybe formed with a single metal via 30 in a ring formation formed insideor outside of the two SiO₂ vias 80. Additionally, the inventioncontemplates that any of the vias may be formed in a continuous orsegmented ring formation. Thus, the invention contemplates differentorientations of the two types of through-wafer via formations.

Performance Analysis

FIG. 16 shows a simulation result graph of substrate noise over a rangeof frequencies comparing noise isolation provided by the presentinvention with noise isolation provided by known structures. As shown inFIG. 16, a known structure having a P+ guard ring and a deep trenchimproves the noise isolation by about 5 dB as compared to a referencestructure having no noise isolation structure. Additionally, a knownstructure having P+ and N+ guard rings and a deep trench improves thenoise isolation by about 9 dB as compared to the reference structure.Furthermore, a known structure having a triple well structure and a deeptrench ring improves the noise isolation by about 10-15 dB as comparedto the reference structure.

In contrast, as shown in FIG. 16, the present invention improves thenoise isolation by approximately 20-30 dB as compared to the referencestructure. Moreover, as shown in FIG. 16, the present invention providesmuch better noise isolation improvement from frequencies of 30 GHz toslightly above 100 GHz than any of known structures. Additionally, asshown in FIG. 16, there may be similar achieved noise isolation for astructure having a metal through-wafer vias 30 and metal layer 90 formedof tungsten, as compared to copper.

Design Flow

FIG. 17 shows a block diagram of an example design flow 900. Design flow900 may vary depending on the type of IC being designed. For example, adesign flow 900 for building an application specific IC (ASIC) maydiffer from a design flow 900 for designing a standard component. Designstructure 920 is preferably an input to a design process 910 and maycome from an IP provider, a core developer, or other design company, ormay be generated by the operator of the design flow, or from othersources. Design structure 920 comprises, e.g., circuit structure 100 inthe form of schematics or HDL, a hardware-description language (e.g.,VERILOG®, Very High Speed Integrated Circuit (VHSIC) HardwareDescription Language (VHDL), C, etc.). VERILOG is a registered trademarkof Cadence Design Systems, Inc. in the United States, other countries,or both. Design structure 920 may be contained on one or more machinereadable medium. For example, design structure 920 may be a text file ora graphical representation of circuit structure 100. Design process 910preferably synthesizes (or translates) circuit structure 100 into anetlist 980, where netlist 980 is, for example, a list of wires,transistors, logic gates, control circuits, I/O, models, etc. thatdescribes the connections to other elements and circuits in anintegrated circuit design and recorded on at least one of machinereadable medium. This may be an iterative process in which netlist 980is resynthesized one or more times depending on design specificationsand parameters for, e.g., the circuit structure 100.

Design process 910 may include using a variety of inputs. For example,the inputs may include inputs from library elements 930, which may housea set of commonly used elements, circuits, and devices, includingmodels, layouts, and symbolic representations, for a given manufacturingtechnology (e.g., different technology nodes, 32 nm, 45 nm, 90 nm,etc.), design specifications 940, characterization data 950,verification data 960, design rules 970, and test data files 985 (whichmay include test patterns and other testing information). Design process910 may further include, for example, standard circuit design processessuch as timing analysis, verification, design rule checking, place androute operations, amongst other inputs. One of ordinary skill in the artof integrated circuit design can appreciate the extent of possibleelectronic design automation tools and applications used in designprocess 910 without deviating from the scope and spirit of theinvention. The design structure of the invention is not limited to anyspecific design flow.

Ultimately, design process 910 preferably translates, e.g., circuitstructure 100, along with the rest of the integrated circuit design (ifapplicable), into a final design structure 990 (e.g., information storedin a graphical data system (GDS) storage medium). Final design structure990 may comprise information such as, for example, test data files,design content files, manufacturing data, layout parameters, wires,levels of metal, vias, shapes, test data, data for routing through themanufacturing line, and any other data required by a semiconductormanufacturer to produce, e.g., circuit structure 100. Final designstructure 990 may then proceed to a stage 995 where, for example, finaldesign structure 990 proceeds to tape-out, is released to manufacturing,is sent to another design house or is sent back to the customer.

While the invention has been described in terms of embodiments, those ofskill in the art will recognize that the invention can be practiced withmodifications and in the spirit and scope of the appended claims.

What is claimed is:
 1. A structure comprising: a substrate comprising aregion having a circuit or device which is sensitive to electrical noiseand electronic noise; a first isolation structure extending through anentire thickness of the substrate and surrounding the region, whereinthe first isolation structure completely surrounds the region; a secondisolation structure extending through the entire thickness of thesubstrate and surrounding the region; and a metal layer formed on anexposed surface of the substrate on an opposing surface from the circuitor device.
 2. The structure of claim 1, wherein the first isolationstructure comprises a metal.
 3. The structure of claim 2, wherein themetal comprises one of copper and tungsten.
 4. The structure of claim 1,wherein the first isolation structure is coupled to the metal layerdisposed on a surface of the substrate on an opposing side from thecircuit or device forming a substantial or entire enclosure about theregion.
 5. The structure of claim 4, wherein the second isolationstructure comprises a dielectric.
 6. The structure of claim 5, whereinthe dielectric comprises SiO₂ and the metal comprises one of tungstenand copper.
 7. The structure of claim 1, wherein the first isolationstructure is formed between the region and the second isolationstructure.
 8. A structure comprising: at least one via filled with adielectric and at least one via filled with metal in a first surface ofa substrate, wherein a second surface portion of the substrate oppositethe first surface of the substrate is removed to expose at least asurface of the metal, wherein the at least one via filled with thedielectric completely surrounds the at least one via filled with themetal; and a metal layer in contact with at least the exposed surface ofthe metal to provide an electrical noise isolation area on thesubstrate.
 9. The structure of claim 8, wherein the dielectric and themetal substantially surround the electrical noise isolation area. 10.The structure of claim 8, wherein: the metal and the metal layercomprise one of copper and tungsten; and the dielectric comprises SiO₂.11. The structure of claim 8, wherein the at least one via filled withmetal is formed between the isolation area and the at least one viafilled with the dielectric.
 12. The structure of claim 8, wherein the atleast one via filled with the dielectric and the at least one via filledwith the metal are formed to be spaced from one another at least aminimum distance.
 13. The structure of claim 1, wherein: the firstisolation structure is filled with metal; and the second isolationstructure is filled with dielectric, wherein the metal layer is incontact with an exposed portion of the first isolation structure and anexposed portion of the second isolation structure.
 14. The structure ofclaim 13, wherein the metal layer extends to edges of the substrate.